Air Qual Atmos Health (2016) 9:533–550 DOI 10.1007/s11869-015-0359-y
Size-segregated urban particulate matter: mass closure, chemical composition, and primary and secondary matter content Wioletta Rogula-Kozłowska 1
Received: 3 April 2015 / Accepted: 1 July 2015 / Published online: 15 July 2015 # The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract Forty-nine components of ambient particulate matter (PM) in size-fractionated PM were investigated at an urban background site in Katowice (Silesian Agglomeration in Southern Poland) in the non-heating season of 2012. PM was analyzed for two groups of carbon compounds (organic (OC) and elemental (EC) carbon, Lab OC-EC Aerosol Analyzer), five major water-soluble ions (NH4+, Cl−, SO42−, NO3−, and Na+ contents in PM water extracts, ion chromatography), 26 elements (X-ray fluorescence spectrometry), and 16 polycyclic aromatic hydrocarbons (PAHs, gas chromatography). The distributions of the masses of these components among 13 basic PM fractions were determined, and chemical mass closure was checked for each of these fractions separately. The particles having their aerodynamic diameters in the interval 0.03–0.26 μm, the fraction PM0.03–0.26, contributed about 13 % to the total PM mass. This PM fraction consisted of primary particles predominantly composed of various inorganic compounds, primary organic compounds, and, in lesser amounts, of elemental carbon, secondary ions, and secondary organic compounds. The second particle fraction, PM0.26–1.6, consisted mainly of secondary matter, and its mass contribution to the total PM mass was about 59 %. The third fraction, PM1.6–40, was a fraction of coarse particles composed of mineral/soil and organic
* Wioletta Rogula-Kozłowska [email protected] 1
Institute of Environmental Engineering, Polish Academy of Sciences, 34 M. Skłodowska-Curie St, 41-819 Zabrze, Poland
matter and elemental carbon. It contributed to the PM mass about 28 %. For each of PM0.03–0.26, PM0.26–1.6, and PM1.6–40, the health hazard from its 16 PAH contents was determined by computing toxicity factors. PM0.26–1.6 posed the greatest health hazard from the mixture of the 16 PAHs that it contained, PM 1.6–40 was the next, and the hazard from the PM0.03–0.26-bound 16 PAHs was the smallest. The molecular diagnostic ratios computed for these three fractions were specific for coal and wood combustion; some indicated the road traffic effects. Keywords Ambient aerosol . Ultrafine particles . Mass size distribution . Health hazard . PAHs
Introduction Among all the air pollutants, airborne particulate matter (PM) affects the environment most extensively. PM impacts negatively on climate and human health (Englert 2004; Pope and Dockery 2006; Paasonen et al. 2013; Atkinson et al. 2015). The PM impact on humans depends on the PM mass and number size distributions. Very small particles of PM (aerodynamic diameters up to 1 μm) are toxic, cytotoxic, and mutagenic; the PM ultrafine fraction (up to 0.1 μm) has the highest oxidative and mutagenic potential (e.g., Massolo et al. 2002; Daher et al. 2014). However, the particle size alone is not decisive in the PM toxicity. Ultrafine PM containing CuO is more harmful to human body cells than micrometric PM, but coarse PM containing TiO2 causes genetic damages more often than the finer PM (Karlsson et al. 2009). In fact, several PM properties mutually tangle to produce the synergistic PM toxic potential, and the size distributions and chemical composition seem to be most important.
534
The chemical composition of PM directly affects the PM volatility, density, reactivity, toxicity, and so on. It accounts for time and space variations in the PM concentrations; it must be taken into account when the PM emissions are to be reduced. Providing basic information on the PM origin, the PM chemistry allows for establishing the source-receptor links. The problems of chemical composition and identification of the sources of PM and of its particular size fractions have been studied intensely over the last years (e.g., Viana et al. 2008; Putaud et al. 2010; Spindler et al. 2010; Belis et al. 2013; Daher et al. 2014; Kong et al. 2014; Huang et al. 2014; Pokorná et al. 2015). However, neither the chemical composition nor the sources of the finest particles, those with aerodynamic diameters up to 1 μm (PM 1 ), are recognized well (Calvo et al. 2013). We know the least about the particles with aerodynamic diameters not greater than 0.1 μm (PM0.1) (Sanderson et al. 2014). The concentrations and chemical composition of PM are very site-dependent; they depend on the local emission sources and the conditions enabling chemical transformations of precursory gaseous compounds. Therefore, the monitoring of the PM concentrations and chemical composition within any area should rely on as dense a network of sampling points as possible. In Central and Eastern Europe, the chemical composition of PM, especially of fine PM (PM1, PM2.5), is not properly monitored because the adequate sampling points are not numerous (Viana et al. 2008; Putaud et al. 2010; Belis et al. 2013; Calvo et al. 2013; Sanderson et al. 2014). The present work is a study of 49 PM chemical components in size-fractionated PM at an urban background site in Katowice (Southern Poland). Two groups of carbon compounds, major water-soluble ions, 16 polycyclic aromatic hydrocarbons, and 26 elements (including toxic metals Ni, Cd, Pb, As) were investigated. These chemicals were determined in 13 basic PM size fractions received directly from the impactor: PM0.03–0.06, PM0.06– 0.108 , PM 0.108–0.17 , PM 0.17–0.26 , PM 0.26–0.4 , PM 0.4–0.65 , PM 0 .65–1 , PM 1– 1.6 , PM 1.6– 2.5 , PM 2.5– 4.4 , PM 4.4– 6.8 , PM6.8–10, and PM10–40 (subscript indexes are the intervals of the particle aerodynamic diameters, μm) and, in some, their superfractions that were defined in the course of the research. Main groups of PM components (mass closure) and contribution of primary and secondary matter and of anthropogenic and natural matter were determined separately for each of the basic fractions and then for some their superfractions. This detailed analysis allowed for the source apportionment of PM emissions in the measuring point neighborhood and provided data on the chemical composition of particular PM fractions, enabling assessment of the health hazard from PM.
Air Qual Atmos Health (2016) 9:533–550
Methods Organization of research and research area The area under research was situated within a big living quarter of Katowice (Silesian Agglomeration), beyond the direct effects of industry and road traffic (Fig. 1). The Silesian Agglomeration lies in the center of Silesia Province, occupies 1230 km2, has about 2.1 million population (1691 inhabitants per one square kilometer). It is one of the most urbanized and industrialized regions in Central Europe. PM was sampled at an urban background sampling point (EC 2008) between the 13 March and the 3 September 2012. Eighteen 13-fold PM samples were taken during the sampling period with the use of a 13-stage DEKATI low-pressure impactor (DLPI, Dekati Ltd.; Kangasala, Finland, flow rate 30 l/ min). The particular sample takings lasted from 123 to 173 h; they covered the whole sampling period in about 70 %. There was no sampling in the winter (heating season), because in Silesia, in winter, the PM chemical composition is totally dominated by carbonaceous municipal emissions (mainly elemental carbon) and is entirely different from the PM composition in the rest of the year (Pastuszka et al. 2010; RogulaKozłowska and Klejnowski 2013; Rogula-Kozłowska et al. 2014). Two kinds of substrates were used, both from Whatman (GE Healthcare Bio-Sciences Corp.; Piscataway, NJ, USA). Alternating between the sample takings, QMA quartz fiber filters, ø25 mm, CAT No. 1851-025 (nine samples), and nylon membrane filters, 0.2 μm, ø25 mm, Cat No. 7402-002 (nine samples), were used, the same substrates on all the impactor stages in one sample taking. Two equal (1.5 cm2) fragments were cut out from each exposed quartz filter just before the analysis; PM on one of them was analyzed for organic carbon (OC) and elemental carbon (EC). The remaining fragments were used to make fraction samples, each by putting together all the nine fragments containing the same PM fraction. These 13 fraction samples were analyzed for the following 16 polycyclic aromatic hydrocarbons (PAHs): naphthalene (Na), acenaphthene (Ace), acenaphthylene (Acy), anthracene (An), benzo [a] anthracene (BaA), benzo [a]pyrene (BaP), benzo[b] fluoranthene (BbF), benzo[k] fluoranthene (BkF), benzo[g, h, i] perylene (BghiP), chrysene (Ch), dibenzo[a, h] anthracene (DBA), fluoranthene (Fl), fluorene (F), phenanthrene (Ph), pyrene (Py), and indeno[1,2,3-cd]pyrene (IP). The PM on the membrane filters was analyzed for the elemental composition (Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Cd, Sb, Te, Ba, and Pb). Then, the concentrations of water-soluble ions (Cl−, SO42−, NO3−, Na+, NH4+) were determined in the PM water extracts.
Air Qual Atmos Health (2016) 9:533–550
535
Fig. 1 The sampling point location
Chemical analyses, QA/QC The substrates and impactors were prepared for exposure in a laminar chamber. The masses of the PM samples were determined by weighing the substrates before and after the exposure; a MYA 5.3Y.F micro balance (1-μg resolution, RADW AG; Radom, Poland) was used. Before each weighing, the substrates were conditioned for 48 h in the weighing room (relative air humidity 45±5 %, air temperature 20±2 °C). After weighing, the exposed filters were put into petri dishes which were wrapped in light-proof aluminum foil and stored in a freezer at −18 °C till the analysis. Blank samples were prepared for each of the 13 basic PM fractions. The four-step process of preparing the blanks consisted of (1) taking out 13 filters from their original package and putting them into Petri dishes; (2) 48-h conditioning of the filters in Petri dishes in the weighing room; (3) loading the Dekati impactor with the filters and installing the impactor at the measuring site for 5 days (pump off); (4) removing the filters from the impactor, putting back into Petri dishes, and 48-h conditioning in the weighing room. The process was repeated for both kinds of filters at the beginning and at the end of the measuring period. The blanks were used to determine the detection limits for the analytical methods and the analyte background levels (the amount of the analyte in a blank, μg, determined for each PM basic fraction separately). Neither PM component analytical background was greater
than 3.5 % of the component content of the PM sample. The analyte content of a PM sample was received by subtracting its background level value from its amount on the exposed filter. The OC and EC contents of PM were determined with the use of a Lab OC-EC Aerosol Analyzer (Sunset Laboratories Inc.; Portland, OR, USA) using the EUSAAR protocol. The measurement performance was controlled by systematic calibrating of the analyzer within the range proper for the determined concentrations and by analyzing standards with certified carbon content (RM 8785 and RM 8786, NIST, Gaithersburg, MD, USA) and the blank samples. The detection limit for total carbon (TC), computed after analyzing the 26 blanks, was 0.52 μg C/cm2 (0.43 and 0.09 μg C/cm2 for OC and EC, respectively). The standard recovery was from 98 to 122 % of the certified value for OC and from 95 to 116 % for EC (the certified values were taken from the IMPROVE program). The detailed description of the extraction procedure and the parameters of the chromatographic analysis of PM for PAHs are in given in Rogula-Kozłowska et al. (2013b). The limits of detection for the 16 PAHs, obtained from the statistical development of the blank results (26 above described quartz fiber filter blanks), were between 6.25 ng (BbF) and 20 ng (Ph). The method performance was verified by analyzing the NIST SRM1649b reference material and comparing the
536
results with the certified concentrations of the investigated PAHs. The standard recoveries were from 92 % (Ph) to 111 % (Acy). The elemental composition of PM was determined by means of energy-dispersive X-ray fluorescence (EDXRF). An Epsilon 5 (PANalytical B.V.; Almelo, The Netherlands), calibrated with the use of thin-layer single-element standards (Micromatter; Vancouver, Canada), was used to measure the total concentrations of the elements. To control the performance of the analytical procedure, the NIST SRM2873 samples were measured weekly (except 52 and 39 % recoveries of V and Co, the recoveries were between 85 and 120 % of the certified values) and the X-ray tube and detector drift monitor monthly. The detection limits (from the statistical development of the blank results) were from 0.15 ng/cm2 (Se) to 16.8 ng/cm2 (Si). The water extracts of PM were made by ultrasonizing the substrates containing the samples in 25 cm3 of de-ionized water for 60 min at the temperature 15 °C and then shaking the extracts for about 12 h (18 °C, 60 r/min). The ion content of the extracts was determined using an ion chromatograph (Metrohm AG; Herisau, Switzerland). The method was validated against the CRM Fluka product nos. 89316 and 89886; the standard recoveries were from 92 % (Na+) to 109 % (Cl−) of the certified values, and the detection limits were as follows: 10 ng/cm3 for NH4+, 18 ng/cm3 for Cl− and SO42−, and 27 ng/cm3 for NO3− and Na+.
Air Qual Atmos Health (2016) 9:533–550
s are computed from the following formulas (Cheng et al. 2005): When the proportion of the concentrations of SO42− and NH4+ (neq/m3; Table 1) is less than 1,
ðNH4 Þ2 SO4
s f
s f ¼ 1:38 SO4 2− A
½NH4 NO3 s f ¼ 4:44½ex−NH4 þ ½ex−NH4 þ
sf
¼ ½NH4 þ
sf
ð2Þ
sf
ð3Þ
A −0:27
ðNH4 Þ2 SO4
s f
ð4Þ
where [SO42−]sfA is the analytically determined mass of SO42− from the fraction f in the sample s, [NH4+]sfA is the analytically determined mass of NH4+ from the fraction f in the sample s, [ex-NH4+]sf amount (mass) of NH4+ from the fraction f left after the reaction with SO42− (excessive NH4+) in the sample s, When the proportion of the concentrations of SO42− and NH4+ (neq/m3; Table 1) is not less than 1,
ðNH4 Þ2 SO4
s f
¼ 3:67 ½NH4 þ
½NH4 NO3 s f ¼ 0
sf A
ð5Þ ð6Þ
Results and discussion Estimation of secondary matter content of size-segregated PM The ambient concentrations of fraction-bound secondary organic carbon (OCsec), ammonium sulfate ((NH4)2SO4), and ammonium nitrate (NH4NO3) were determined from the analytically determined amounts of OC, EC, SO42−, and NH4+ in PM. The mass [OCsec]sf of the OCsec from the basic fraction f in the sample s is computed from the equation (Castro et al. 1999): ! ½OC f A sf sf ½OCsec ¼ ½OC A − :½ECs f A ð1Þ ½EC f A min where [OC]sfA is the analytically determined mass of the OC from the fraction f in the sample s, [EC]sfA is the analytically determined mass of the EC from the fraction f in the sample s, ([OC]fA/[EC]fA)min is the smallest [OC]sfA/[EC]sfA for all the samples s of the fraction f (([OC]fA/[EC]fA)min for all the PM fractions are presented in Table 1). The masses [(NH 4 ) 2 SO 4 ] sf and [NH 4 NO 3 ] sf of the (NH4)2SO4 and NH4NO3 in the basic fraction f in the sample
Concentration and mass size distribution of PM and PM components The minima, maxima, and averages in the measuring period of ambient concentrations for each substance determined analytically in each basic PM fraction, except for the 16 PAHs whose extreme concentrations were not measured, are presented in Table 1; together with the values of some parameters employed in computing, these values for the ambient concentrations of OCsec, (NH4)2SO4, and NH4NO3 are also presented in Table 1. In Katowice, the core PM mass was due to PM0.26–1.6 (Table 1). The measuring period average PM0.26–1.6 concentration was 14.5 μg/m3, about 60 % of the PM10 concentration. The remaining 40 % was divided between PM0.03–0.26 and PM1.6–10 in the proportion of 1:2. The masses of the main PM components were also concentrated in PM0.26–1.6. By mass, about 50 % of Cl−, 60 % of NO3−, 70 % of OC and SO42−, and 80 % of Na+ were in PM0.26–1.6, from 11 % (Na+) to 21 % (Cl−) in PM0.03–0.26, and from 10 % (Na+) to 40 % (EC) in PM1.6–10. The density function of the PM mass distribution with respect to particle size has its absolute (greatest local) maximum
d
0.03 0.25 1.83 2.06 1.38 1.97 0.67 1.04 1.34 1.50 0.38 0.47 10.41 14.25 1.31 1.78 0.42 0.65 2.91 3.92 0.94 1.24 0.20 0.28 0.01
∑anions/∑cationsk
Ni
Co
Fe
Mn
Cr
V
Ti
Sc
Ca
K
Si
Al
0.00
173.46 277.25c 68.12 84.39 4.97 7.78 7.34 11.84 0.00 27.31
Size-segregated urban particulate matter: mass closure, chemical composition, and primary and secondary matter content Wioletta Rogula-Kozłowska 1
Received: 3 April 2015 / Accepted: 1 July 2015 / Published online: 15 July 2015 # The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract Forty-nine components of ambient particulate matter (PM) in size-fractionated PM were investigated at an urban background site in Katowice (Silesian Agglomeration in Southern Poland) in the non-heating season of 2012. PM was analyzed for two groups of carbon compounds (organic (OC) and elemental (EC) carbon, Lab OC-EC Aerosol Analyzer), five major water-soluble ions (NH4+, Cl−, SO42−, NO3−, and Na+ contents in PM water extracts, ion chromatography), 26 elements (X-ray fluorescence spectrometry), and 16 polycyclic aromatic hydrocarbons (PAHs, gas chromatography). The distributions of the masses of these components among 13 basic PM fractions were determined, and chemical mass closure was checked for each of these fractions separately. The particles having their aerodynamic diameters in the interval 0.03–0.26 μm, the fraction PM0.03–0.26, contributed about 13 % to the total PM mass. This PM fraction consisted of primary particles predominantly composed of various inorganic compounds, primary organic compounds, and, in lesser amounts, of elemental carbon, secondary ions, and secondary organic compounds. The second particle fraction, PM0.26–1.6, consisted mainly of secondary matter, and its mass contribution to the total PM mass was about 59 %. The third fraction, PM1.6–40, was a fraction of coarse particles composed of mineral/soil and organic
* Wioletta Rogula-Kozłowska [email protected] 1
Institute of Environmental Engineering, Polish Academy of Sciences, 34 M. Skłodowska-Curie St, 41-819 Zabrze, Poland
matter and elemental carbon. It contributed to the PM mass about 28 %. For each of PM0.03–0.26, PM0.26–1.6, and PM1.6–40, the health hazard from its 16 PAH contents was determined by computing toxicity factors. PM0.26–1.6 posed the greatest health hazard from the mixture of the 16 PAHs that it contained, PM 1.6–40 was the next, and the hazard from the PM0.03–0.26-bound 16 PAHs was the smallest. The molecular diagnostic ratios computed for these three fractions were specific for coal and wood combustion; some indicated the road traffic effects. Keywords Ambient aerosol . Ultrafine particles . Mass size distribution . Health hazard . PAHs
Introduction Among all the air pollutants, airborne particulate matter (PM) affects the environment most extensively. PM impacts negatively on climate and human health (Englert 2004; Pope and Dockery 2006; Paasonen et al. 2013; Atkinson et al. 2015). The PM impact on humans depends on the PM mass and number size distributions. Very small particles of PM (aerodynamic diameters up to 1 μm) are toxic, cytotoxic, and mutagenic; the PM ultrafine fraction (up to 0.1 μm) has the highest oxidative and mutagenic potential (e.g., Massolo et al. 2002; Daher et al. 2014). However, the particle size alone is not decisive in the PM toxicity. Ultrafine PM containing CuO is more harmful to human body cells than micrometric PM, but coarse PM containing TiO2 causes genetic damages more often than the finer PM (Karlsson et al. 2009). In fact, several PM properties mutually tangle to produce the synergistic PM toxic potential, and the size distributions and chemical composition seem to be most important.
534
The chemical composition of PM directly affects the PM volatility, density, reactivity, toxicity, and so on. It accounts for time and space variations in the PM concentrations; it must be taken into account when the PM emissions are to be reduced. Providing basic information on the PM origin, the PM chemistry allows for establishing the source-receptor links. The problems of chemical composition and identification of the sources of PM and of its particular size fractions have been studied intensely over the last years (e.g., Viana et al. 2008; Putaud et al. 2010; Spindler et al. 2010; Belis et al. 2013; Daher et al. 2014; Kong et al. 2014; Huang et al. 2014; Pokorná et al. 2015). However, neither the chemical composition nor the sources of the finest particles, those with aerodynamic diameters up to 1 μm (PM 1 ), are recognized well (Calvo et al. 2013). We know the least about the particles with aerodynamic diameters not greater than 0.1 μm (PM0.1) (Sanderson et al. 2014). The concentrations and chemical composition of PM are very site-dependent; they depend on the local emission sources and the conditions enabling chemical transformations of precursory gaseous compounds. Therefore, the monitoring of the PM concentrations and chemical composition within any area should rely on as dense a network of sampling points as possible. In Central and Eastern Europe, the chemical composition of PM, especially of fine PM (PM1, PM2.5), is not properly monitored because the adequate sampling points are not numerous (Viana et al. 2008; Putaud et al. 2010; Belis et al. 2013; Calvo et al. 2013; Sanderson et al. 2014). The present work is a study of 49 PM chemical components in size-fractionated PM at an urban background site in Katowice (Southern Poland). Two groups of carbon compounds, major water-soluble ions, 16 polycyclic aromatic hydrocarbons, and 26 elements (including toxic metals Ni, Cd, Pb, As) were investigated. These chemicals were determined in 13 basic PM size fractions received directly from the impactor: PM0.03–0.06, PM0.06– 0.108 , PM 0.108–0.17 , PM 0.17–0.26 , PM 0.26–0.4 , PM 0.4–0.65 , PM 0 .65–1 , PM 1– 1.6 , PM 1.6– 2.5 , PM 2.5– 4.4 , PM 4.4– 6.8 , PM6.8–10, and PM10–40 (subscript indexes are the intervals of the particle aerodynamic diameters, μm) and, in some, their superfractions that were defined in the course of the research. Main groups of PM components (mass closure) and contribution of primary and secondary matter and of anthropogenic and natural matter were determined separately for each of the basic fractions and then for some their superfractions. This detailed analysis allowed for the source apportionment of PM emissions in the measuring point neighborhood and provided data on the chemical composition of particular PM fractions, enabling assessment of the health hazard from PM.
Air Qual Atmos Health (2016) 9:533–550
Methods Organization of research and research area The area under research was situated within a big living quarter of Katowice (Silesian Agglomeration), beyond the direct effects of industry and road traffic (Fig. 1). The Silesian Agglomeration lies in the center of Silesia Province, occupies 1230 km2, has about 2.1 million population (1691 inhabitants per one square kilometer). It is one of the most urbanized and industrialized regions in Central Europe. PM was sampled at an urban background sampling point (EC 2008) between the 13 March and the 3 September 2012. Eighteen 13-fold PM samples were taken during the sampling period with the use of a 13-stage DEKATI low-pressure impactor (DLPI, Dekati Ltd.; Kangasala, Finland, flow rate 30 l/ min). The particular sample takings lasted from 123 to 173 h; they covered the whole sampling period in about 70 %. There was no sampling in the winter (heating season), because in Silesia, in winter, the PM chemical composition is totally dominated by carbonaceous municipal emissions (mainly elemental carbon) and is entirely different from the PM composition in the rest of the year (Pastuszka et al. 2010; RogulaKozłowska and Klejnowski 2013; Rogula-Kozłowska et al. 2014). Two kinds of substrates were used, both from Whatman (GE Healthcare Bio-Sciences Corp.; Piscataway, NJ, USA). Alternating between the sample takings, QMA quartz fiber filters, ø25 mm, CAT No. 1851-025 (nine samples), and nylon membrane filters, 0.2 μm, ø25 mm, Cat No. 7402-002 (nine samples), were used, the same substrates on all the impactor stages in one sample taking. Two equal (1.5 cm2) fragments were cut out from each exposed quartz filter just before the analysis; PM on one of them was analyzed for organic carbon (OC) and elemental carbon (EC). The remaining fragments were used to make fraction samples, each by putting together all the nine fragments containing the same PM fraction. These 13 fraction samples were analyzed for the following 16 polycyclic aromatic hydrocarbons (PAHs): naphthalene (Na), acenaphthene (Ace), acenaphthylene (Acy), anthracene (An), benzo [a] anthracene (BaA), benzo [a]pyrene (BaP), benzo[b] fluoranthene (BbF), benzo[k] fluoranthene (BkF), benzo[g, h, i] perylene (BghiP), chrysene (Ch), dibenzo[a, h] anthracene (DBA), fluoranthene (Fl), fluorene (F), phenanthrene (Ph), pyrene (Py), and indeno[1,2,3-cd]pyrene (IP). The PM on the membrane filters was analyzed for the elemental composition (Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Cd, Sb, Te, Ba, and Pb). Then, the concentrations of water-soluble ions (Cl−, SO42−, NO3−, Na+, NH4+) were determined in the PM water extracts.
Air Qual Atmos Health (2016) 9:533–550
535
Fig. 1 The sampling point location
Chemical analyses, QA/QC The substrates and impactors were prepared for exposure in a laminar chamber. The masses of the PM samples were determined by weighing the substrates before and after the exposure; a MYA 5.3Y.F micro balance (1-μg resolution, RADW AG; Radom, Poland) was used. Before each weighing, the substrates were conditioned for 48 h in the weighing room (relative air humidity 45±5 %, air temperature 20±2 °C). After weighing, the exposed filters were put into petri dishes which were wrapped in light-proof aluminum foil and stored in a freezer at −18 °C till the analysis. Blank samples were prepared for each of the 13 basic PM fractions. The four-step process of preparing the blanks consisted of (1) taking out 13 filters from their original package and putting them into Petri dishes; (2) 48-h conditioning of the filters in Petri dishes in the weighing room; (3) loading the Dekati impactor with the filters and installing the impactor at the measuring site for 5 days (pump off); (4) removing the filters from the impactor, putting back into Petri dishes, and 48-h conditioning in the weighing room. The process was repeated for both kinds of filters at the beginning and at the end of the measuring period. The blanks were used to determine the detection limits for the analytical methods and the analyte background levels (the amount of the analyte in a blank, μg, determined for each PM basic fraction separately). Neither PM component analytical background was greater
than 3.5 % of the component content of the PM sample. The analyte content of a PM sample was received by subtracting its background level value from its amount on the exposed filter. The OC and EC contents of PM were determined with the use of a Lab OC-EC Aerosol Analyzer (Sunset Laboratories Inc.; Portland, OR, USA) using the EUSAAR protocol. The measurement performance was controlled by systematic calibrating of the analyzer within the range proper for the determined concentrations and by analyzing standards with certified carbon content (RM 8785 and RM 8786, NIST, Gaithersburg, MD, USA) and the blank samples. The detection limit for total carbon (TC), computed after analyzing the 26 blanks, was 0.52 μg C/cm2 (0.43 and 0.09 μg C/cm2 for OC and EC, respectively). The standard recovery was from 98 to 122 % of the certified value for OC and from 95 to 116 % for EC (the certified values were taken from the IMPROVE program). The detailed description of the extraction procedure and the parameters of the chromatographic analysis of PM for PAHs are in given in Rogula-Kozłowska et al. (2013b). The limits of detection for the 16 PAHs, obtained from the statistical development of the blank results (26 above described quartz fiber filter blanks), were between 6.25 ng (BbF) and 20 ng (Ph). The method performance was verified by analyzing the NIST SRM1649b reference material and comparing the
536
results with the certified concentrations of the investigated PAHs. The standard recoveries were from 92 % (Ph) to 111 % (Acy). The elemental composition of PM was determined by means of energy-dispersive X-ray fluorescence (EDXRF). An Epsilon 5 (PANalytical B.V.; Almelo, The Netherlands), calibrated with the use of thin-layer single-element standards (Micromatter; Vancouver, Canada), was used to measure the total concentrations of the elements. To control the performance of the analytical procedure, the NIST SRM2873 samples were measured weekly (except 52 and 39 % recoveries of V and Co, the recoveries were between 85 and 120 % of the certified values) and the X-ray tube and detector drift monitor monthly. The detection limits (from the statistical development of the blank results) were from 0.15 ng/cm2 (Se) to 16.8 ng/cm2 (Si). The water extracts of PM were made by ultrasonizing the substrates containing the samples in 25 cm3 of de-ionized water for 60 min at the temperature 15 °C and then shaking the extracts for about 12 h (18 °C, 60 r/min). The ion content of the extracts was determined using an ion chromatograph (Metrohm AG; Herisau, Switzerland). The method was validated against the CRM Fluka product nos. 89316 and 89886; the standard recoveries were from 92 % (Na+) to 109 % (Cl−) of the certified values, and the detection limits were as follows: 10 ng/cm3 for NH4+, 18 ng/cm3 for Cl− and SO42−, and 27 ng/cm3 for NO3− and Na+.
Air Qual Atmos Health (2016) 9:533–550
s are computed from the following formulas (Cheng et al. 2005): When the proportion of the concentrations of SO42− and NH4+ (neq/m3; Table 1) is less than 1,
ðNH4 Þ2 SO4
s f
s f ¼ 1:38 SO4 2− A
½NH4 NO3 s f ¼ 4:44½ex−NH4 þ ½ex−NH4 þ
sf
¼ ½NH4 þ
sf
ð2Þ
sf
ð3Þ
A −0:27
ðNH4 Þ2 SO4
s f
ð4Þ
where [SO42−]sfA is the analytically determined mass of SO42− from the fraction f in the sample s, [NH4+]sfA is the analytically determined mass of NH4+ from the fraction f in the sample s, [ex-NH4+]sf amount (mass) of NH4+ from the fraction f left after the reaction with SO42− (excessive NH4+) in the sample s, When the proportion of the concentrations of SO42− and NH4+ (neq/m3; Table 1) is not less than 1,
ðNH4 Þ2 SO4
s f
¼ 3:67 ½NH4 þ
½NH4 NO3 s f ¼ 0
sf A
ð5Þ ð6Þ
Results and discussion Estimation of secondary matter content of size-segregated PM The ambient concentrations of fraction-bound secondary organic carbon (OCsec), ammonium sulfate ((NH4)2SO4), and ammonium nitrate (NH4NO3) were determined from the analytically determined amounts of OC, EC, SO42−, and NH4+ in PM. The mass [OCsec]sf of the OCsec from the basic fraction f in the sample s is computed from the equation (Castro et al. 1999): ! ½OC f A sf sf ½OCsec ¼ ½OC A − :½ECs f A ð1Þ ½EC f A min where [OC]sfA is the analytically determined mass of the OC from the fraction f in the sample s, [EC]sfA is the analytically determined mass of the EC from the fraction f in the sample s, ([OC]fA/[EC]fA)min is the smallest [OC]sfA/[EC]sfA for all the samples s of the fraction f (([OC]fA/[EC]fA)min for all the PM fractions are presented in Table 1). The masses [(NH 4 ) 2 SO 4 ] sf and [NH 4 NO 3 ] sf of the (NH4)2SO4 and NH4NO3 in the basic fraction f in the sample
Concentration and mass size distribution of PM and PM components The minima, maxima, and averages in the measuring period of ambient concentrations for each substance determined analytically in each basic PM fraction, except for the 16 PAHs whose extreme concentrations were not measured, are presented in Table 1; together with the values of some parameters employed in computing, these values for the ambient concentrations of OCsec, (NH4)2SO4, and NH4NO3 are also presented in Table 1. In Katowice, the core PM mass was due to PM0.26–1.6 (Table 1). The measuring period average PM0.26–1.6 concentration was 14.5 μg/m3, about 60 % of the PM10 concentration. The remaining 40 % was divided between PM0.03–0.26 and PM1.6–10 in the proportion of 1:2. The masses of the main PM components were also concentrated in PM0.26–1.6. By mass, about 50 % of Cl−, 60 % of NO3−, 70 % of OC and SO42−, and 80 % of Na+ were in PM0.26–1.6, from 11 % (Na+) to 21 % (Cl−) in PM0.03–0.26, and from 10 % (Na+) to 40 % (EC) in PM1.6–10. The density function of the PM mass distribution with respect to particle size has its absolute (greatest local) maximum
d
0.03 0.25 1.83 2.06 1.38 1.97 0.67 1.04 1.34 1.50 0.38 0.47 10.41 14.25 1.31 1.78 0.42 0.65 2.91 3.92 0.94 1.24 0.20 0.28 0.01
∑anions/∑cationsk
Ni
Co
Fe
Mn
Cr
V
Ti
Sc
Ca
K
Si
Al
0.00
173.46 277.25c 68.12 84.39 4.97 7.78 7.34 11.84 0.00 27.31
